Mitsubishi Electric Mr.SLIM PLA-SM71EA Service Manual page 32

9-6-1. Thermistor
<Thermistor Characteristic Graph>
Thermistor for
lower temperature
Thermistor R =15k" ± 3%
0
Fixed number of B=3480 ± 2%
1
Rt=15exp { 3480(
273+t
0: 15 k"
10: 9.6 k"
20: 6.3 k"
25: 5.4 k"
30: 4.3 k"
40: 3.0 k"
9-6-2. DC Fan motor (FAN MOTOR/INDOOR CONTROLLER BOARD)
Check method of DC fan motor (fan motor / indoor controller circuit board)
Notes
1
· High voltage is applied to the connector (CNMF) for the fan motor. Pay attention to the service.
· Do not pull out the connector (CNMF) for the motor with the power supply on.
(It causes trouble of the indoor controller circuit
Self check
2
Symptom : The indoor fan cannot turn around.
Wiring contact check
The contact of fan motor connect (CNMF)
Is there contact failure? (loose connector, insert failure)
No
Power supply check (Without fan motor connected)
Remove the fan motor (Remove the fan motor connector CNMF) and measure the
voltage in the indoor controller circuit
TEST POINT 1 : V (between 1 (+) and 4 (-) of the fan motor connector): V
DC
TEST POINT
2 : V (between 5 (+) and 4 (-) of the fan motor connector): V
CC
Is the voltage normal?
No
OCH683
Room temperature thermistor (TH1)
Pipe temperature thermistor/liquid (TH2)
Condenser/evaporator temperature
thermistor (TH5)
1
) }
273
board and fan motor.)
board.
Yes
Replace defective fan motor.
Note: If the indoor fan does not operate after replacing the
Replace indoor controller board.
Note: If the indoor fan does not operate after replacing the
Wiring recovery
310-340 V DC
DC
15 V DC
CC
fan motor, also replace the indoor controller board.
indoor controller board, also replace the fan motor.
32
< Thermistor for lower temperature >
50
40
30
20
10
0
-20 -10 0 10 20 30 40 50
Temperature (:)